A recent article in the "Scientific American", (Feb. 1984, Timothy A. Salthouse, The Skill of Typing, pages 128-135), focuses on the psychological aspects of typing speed, but the author admits that a century of study has not produced a definitive answer, short of several hypotheses. The article does not discuss the contribution of the interface of the key, namely its upper surface, with the fingertips of an operator. The conventional shape of the upper surface of a key is either concave, or flat, or flat bordered by an upwardly extending rim.